The present invention relates to a food measuring device and, more particularly, to a food weight measuring device for a cooking apparatus such as microwave oven which can exactly measure the weight of food disposed in a heating chamber based on a change in electrostatic capacity. The present invention further relates to the construction of a food weight measuring device which prevents liquid or dust from being introduced into the food weight measuring device.
In a microwave oven of the prior art related to the present invention, a food weight measuring device is provided with a turntable mechanism in a heating chamber so as to measure the weight of food disposed on the turntable. The food weight measuring device is provided for automatically heating the food based on the weight of food, and automatically carries out the weight measuring operation when the food is disposed on the turntable. For example, a food weight measuring device is disclosed in U.S. patent application Ser. No. 724,072 filed on Apr. 16, 1985, now U.S. Pat. No. 4,615,405, entitled "FOOD WEIGHT MEASURING DEVICE FOR COOKING APPLIANCE" by Taisuke MORINO et al. The British counterpart is application No. 8509781 filed on Apr. 17, 1985, and the counterpart in West Germany is application No. P3514505.6 filed on Apr. 20, 1985.
However, if liquid such as water, coffee etc. is dropped on the turntable, the dropped liquid may flow into a shaft bearing, a condenser portion and an electrode portion of the food weight measuring device via a turntable shaft. This liquid damages the measuring operation so that the weight of the food cannot be exactly measured by the device. Because the weight of the food cannot be exactly measured, the desired heating operation cannot be automatically selected and cannot be carried out. Also, fine dust may invade the food weight measuring device, so that the weight of food cannot be exactly measure.
Accordingly, it is desired that a novel food weight measuring device be provided to exactly measure the weight of the food stored on the turntable even when liquid is dropped on the turntable and dust is present from the surrounding.